The Case For Clean Diesel

By Alison Lakin

I tend to think of ecological automotive solutions like weight loss. Or, rather, attempts at weight loss. Crash diets are a temporary fix, which can help you shed those five pounds in time for your 10-year reunion, but come six months later, you’ll be right back where you started, if not worse off. Instead, long-term and steady solutions work best - which happen to be the most agonizing way of doing things.

Our car market is currently reading up on some potential consumption reduction techniques now that the gluttonous SUV binge has slowed and fuel-efficiency is a hot topic. Vehicles running on electricity alone, hydrogen and even compressed natural gas are on the table as options. All are helpful in cutting down on America's oil consumption, but aren’t as quick as, say, the Cabbage Soup Diet, thanks to a lack of infrastructure, popular support, charging times and the list goes on.

What to do in the interim, while America prepares for its acceptance of these slow-to-arrive bringers of super efficient transportation? Ah, that’s where diesel comes in. We tried it once back in the ‘70s and it didn’t particularly sit well with us. For years now, it’s been a very European way of doing things. Think French Women Don’t Get Fat for the automotive set. But automakers have revisited the low-fat technology with some surprising developments.

While Toyota has been raking in the big bucks with its hybrid car, the Prius, VW, Mercedes-Benz, BMW and Audi have been in their collective workshops prepping to be the first to bring ‘clean’ diesel engines to the U.S. Changes have been made from the fuel refinement process all the way to emissions control at the tailpipe, equating to a more fuel-efficient and eco-conscious ride. Gone are the stinky, loud and underpowered qualities found in models from the 1970s.

These new models have emissions equal to those 35-plus mpg econoboxes and better than some hybrids even – but with double the amount of torque. Hello, power! As for the noise, strain your ears during acceleration and you may notice a slightly different engine note.

Unlike hybrids that shut off at a stop, diesels need to burn fuel while waiting at a light. No matter how much better the mileage is over gasoline-powered cars, diesel’s city mpgs can’t reach those hybrid levels yet. However, get one on the freeway and you have an impressive contender. The Volkswagen Jetta TDI, originally rated by the EPA at 29 mpg city and 40 mpg highway, was also third-party tested by AMCI at an even more fuel-efficient 38 city and 44 highway. Those numbers are right up there with the compact hybrid-electric cars on the road today, and this is all done without the added pounds (better watch your cupcake intake, lead-acids) from toxic batteries powering the vehicle, an issue with hybrids that has environmentalists worried.

An essential reason the clean diesels sweep through emissions standards now is their use of highly refined Ultra Low Sulfur Diesel (ULSD). Compared to old-school diesel, ULSD has 97 percent less sulfur in it. Goodbye funky smell! The cleaner fuel became available in the U.S. during 2006 and is now found at almost every service station that carries diesel.

With the introduction of this cleaner fuel, U.S. spec diesels can make use of particulate filters and urea injection systems to reduce emissions to even lower than their gasoline powered stable mates. These systems can decrease the amount of particulate matter from the exhaust system by 90 percent. Mercedes-Benz BlueTEC diesels and others also use an additive in the catalytic converter to change normally harmful and polluting gases into harmless nitrogen and water.

Additionally, our infrastructure is already set up to support diesel use, giving it the advantage over other options like compressed natural gas (CNG) or hydrogen. And since more than 50 percent of fuelling stations carry diesel, buyers won't have to worry over whether or not they can find a station.

Another fun fact: Diesel engines produce massive amounts of torque – no wonder they remain the fuel of choice for truckers. And it's a characteristic that makes driving them far more entertaining than tooling around in a hybrid. SUVs powered by this type of fuel receive the same low-end torque as big rigs, helping the lumbering vehicles get up to speed more quickly.

In smaller cars, the heapings of torque balance out the lack of horsepower. The same can’t be said for CNG, which decreases the Honda Civic’s horsepower by 27 when used in its exclusive GX trim. And hybrids? They tend to be ho-hum off the line as well.

Considering they receive an overall 20-30 percent savings in fuel economy, diesel is an applicable and currently feasible way to return low emissions and reduce overall oil usage in America.

Clean diesels are coming out of the woodworks and onto dealer floors. Their performance, mileage and already accessible infrastructure make them the first front in staunching our voracious appetite for fuel.

Now, you may ask, which carmakers are actually investing in this technology? Here's a list of the models currently available.